Electric pump



May 5, 1931.

H. H. COBE ELECTRIC PUMP Filed Feb. 16, 1927 2 Sheets-Sheet 2 ATTCIRNEy- Patented May 5, 1931 UNITED STATES PATENT OFFICE HARRY H. COBE, OF CHELSEA, MASSACHUSETTS, ASSIGNOR, BY DIRECT AND MESNE ASSIGNMENTS, TO COBE ENGINEERING COMPANY, OFn BOSTON, MASSACHUSETTS, Ay

CORPORATION OF MASSACHUSETTS ELECTRIC PUMP Application led February 16, 1927. Serial No. 168,630.

This invention relates to pumps and particularly to pumps for use as compressors for mechanical refrigerating systems.

Heretofore, it has been common to construct a pump or compressor with a piston or compression element movable within a cylinder or compression chamber and actuated through a connecting member, such as a piston rod, extending through the outer casing 1o or cylinder head. The opening in the outer casing or cylinder head between the actuating element, such as the piston rod, has been illed by packing. It has been dittcult, and in fact impossible, to provide packing for this purpose which would give long continued eiicient service without permitting leakage.

It is'an object of the present invention to provide a pump or compressor in which such diiiiculties areminimized or eliminated and such that when used as a compressor for compressing refrigerants the damage caused to the parts of the compressor or pump by leakage ofthe refrigerant is minimized. lVith this in view the invention particularly contemplates the provision of a pump or compressor in which the compression element is wholly enclosed within the compression chamber and actuated in such\a manner that there are no moving parts extending from the interior to the exterior of the compression lchamber thereby Igreatly simplifying the packing problems.

These and other objects of the invention will be more cle-arly understood from the following description in conjunction with the accompanying drawings, in which:

Fig. 1 is a longitudinal sectional elevational view of a pump or compressor embodying the invention.

Fig. 2 is a plan View of the same partly in section.

Figs. 3 and 4 are longitudinal sectional elevational and plan views respectively of the same illustrating the position of the various parts during movement of the compression element or piston.

Fig. 5 is a longitudinal sectional elevational view of the same showing the arrangement of parts when the compression element is at one end of its stroke; and

Fig. 6 is a sectional elevational View taken upon the line 6 6, of Fig. 2.

rPhe pump or compressor specifically illustratcd in the drawings comprises a cylinder casing 10 providing a compression chamber 11 Vand is provided with an intake opening or port 12 near the central portion thereof. The outer surface of the casing is provided with a flat portion to which plates 13 are secured as by screws 48, said plates providing suitable slideways 14 for a slide referred to more fully hereinafter.

The ends of the cylinder are entirely closed by heads 15 secured to the cylinder by bolts 16 engaging flanges 17 at the ends of the cylinder. Each cylinder head is formed with a relatively large portion 18 and a reduced central portion 19. The cylinder heads are provided with alined axial bores 20 constituting guides for a pair of alined piston rods 21 projecting in opposite directions from the opposite faces of a piston 22. Each piston rod is provided with an annular groove 23 adjacent the face of the piston. An annular groove 24: is provided in each cylinder head within the bore 2O and communicates directly with an exhaust port or opening 25. r1`he reduced portion 19 of each cylinder head is enclosed by the coil 26 of the electro-magnet-ic device or solenoid of which the reduced portion 19 of the cylinder head constitutes the core and the enlarged portion 18 a pole piece, the cylinder heads being composed of suitable electro-magnetic material such as softiron. The coil 26 is suitably hold in place against the portion 1S of the cylinder head by a plate 27 secured to the cylinder head in any suitable manner as by screws 28. A by-pass opening 29 extends through the piston 22 and the piston rods 21 so as to permit the flow of fluid between the bores 2() during movement of the piston. I

The electro-magnetic devices are energized from any suitable source of electric current, such asia battery 30, one terminal of which grounded, indicated at 31, and the other terminal of which is connected with the coil 26 at the right by a conductor 52. A conductor 33 leads from the coil 26 to the contact post 3l of an electric switch. The circuit les is grounded through the cylinder casing and parts described later. The cuil 26 'at the left is connected to the battery 30 by a conductor and to the contact post 36 of the switch by a conductor 37. The contact posts 34 and 36 are set in suitable insulators 38 so that their top surfaces are flush with the outer' flat portion of the cylinder.

In order that the electro-magnetic devices may be alternately energized and de-energized to reciprocate the piston within the cylinder, an automatically operated switch is provided adapted to complete the break alternately the circuits leading from the battery 30. A suitable switch for this purpose'may comprise a slide 53 operating in the slideways 14 and having its ends arranged in proximity to the pole pieces 18 of the solenoids, whereby said slide is permitted a limited reciprocatory movement in said slideways between said pole pieces. T he slide 53 is provided with an opening providing slideways 54 engaged by a second slide 55 of suitable insulating material having openings 56 to receive suitable electrical contacts 57 and 58which are yieldingly held against the outer flat portion of the casing 10 by a leaf spring 59 engaging the outer ends of the contacts 57 and 58 and adjustably mounted upon the slide 55 by a screw 60. A

spring 61 is secured to the slide 55 and extends to and is secured to posts 62 upon the slide 53 in order to move the slide as explained hereinafter in response to movements of the slide 53.

The movements of the latter slide in its slideways 14 are retarded by a dash-pot device comprising a plunger 45 operatin g in a cylinder 46 formed in a casing 47 having ears 49 secured to one of the plates 13, as by the screws 48 which secure said plates to the dat portion of the casing 10. The plunger 45 is connected with the slide 53 by an arm 51 projecting from said plunger through a slot 5,0 in the wall of the casing 47. A by-pass 63 is provided in the Wall of the casing 47 leading to opposite ends of the cylinder 46 to permit the flow of a suitable fluid, such as glycerine, during movement of the plunger 45. An adjusting screw 64 serving as a valve is pro` vided in the casing 47 to control the iiow of fluid through the by-pass 63.

A pair of movable stop arms 65 and 66 are l slidably mounted within openings 67 in lugs 68 projecting from the other plate 13. The stop arm 65 is provided with a pin 70 and the stop arm 66 is provided with a similar pin 71 projecting therefrom and between` movement bythe stop 65.

7 2. The stop arm 65 is so positioned as to move inwardly within the path of and engage one end of the slide 55 when the Contact 57 engages the post 36, and the stop arm 66 is so positioned as tomove inwardly in response to the action of the spring 72 to engage the opposite end of the slide when it has been moved to a position such that the contact 58 engages the post 34. The position and movement of the stop arms 65 and 66 is controlled by positioning the pins and 71 thereon within the paths respectively of the cams 74 and 75 mounted upon the slide In the construction illustrated, one of the contacts 57 and58 will always be held in engagement with one of the Contact posts 34 and 36. As illustrated in Figs. 1 to 4 the contact 57 is held in engagement with the contact post 36 by the stop arm 65 engaging the end of the slide 55. It will be noted that the electrical circuit is completed through the spring 59, contact 58, and casing 10 which is grounded as indicated at 76. lVhen thus positioned the solenoid coil at the left is energized, thereby causing its pole piece 18 toattract the slide 53 and tending to move the latter toward the left, this movement being retarded by the dash pot plunger 45. This movement of the slide 53 supplies the spring 61 with potential energy tending to m'ovc the slide 55 in the same direction, the latter slide, however, being at this time held against such The relative positions of the plunger 45, slides 53 and and spring 61 during such movement are illustrated by a comparison of Figs. 2 and 4. The device is so constructed and arranged4 that when the piston 22 has reached the end of its stroke (as viewed in Fig. 5) the cam 74, which moves in unison with the slide 53, as retarded by the plunger 45, is brought to a position such as to engage the pin 70 and withdraw the stop arm 65 from the slide 55 and permit the latter to be moved to the left by the spring 61. l

This movement oi the slide 55 brings the contact 58 into engagement with the contact post 34 thereby completing the electrical circuit through the solenoid coil on the right (as Viewed in Fig. 5).. At the same time the stop arm 66 is moved inwardly due to the action of the spring 72 to engage the end of the slide 55 and prevent its movement toward the right. It will be understood that the solenoid coil on the right now is energized and the slide 53, as well as the piston 22, is drawnV to the right againstthe retarding influence of the plunger 45. lVhen the piston has moved towards the right to reach the end ot its stroke the cam 75, which is also moving toward the right in unison with the slide 53, will engage the pin 71 to depress the stop arm 66 and release it from engagement withthe slide 55 whereupon the latter will move toward the right so as to bring the Leogancontact 57 again into engagement with the contact post. 36. These operations are alternately taking place to energize lirst one solenoid coil and then the other to reciprocate the piston 22 back and forth. The arrangement is such that when the piston is at the end of its stroke a suitable refrigerant is permitted to pass into the cylinder through the inlet port 1Q and undergoes compression until the annular groove Q3 on the piston rod 2l is brought beneath the annular groove 24: whereupon the refrigerant is permitted to expand rapidly by escaping through the eX- haust port It will be observed that the mechanism described provides means, located wholly outside the pump cylinder, for controlling the movements of the piston within the latter, there being no mechanical connections between the piston and its controlling means extending through the wall of the cylinder, the latter, except for the inlet and exhaust ports, being completely closed, thereby obviating all leakage and packing problems. It will also be seen that the same solenoids are employed for actuating both the pump piston and the controlling switch, thereby resulting in an exceedingly simple, compact, and inexpensive construction.

What I claim is: i l. In a pump, in combination, a pump cyl- Inder having an inlet and an outlet port, a cylinder head entirely enclosing each end ot' the cylinder, a piston reciprocable within the cylinder, an electro-magnetic device for moving the piston in each direction, an electrical supply source, a pair of spaced contact posts each electrically connected with one et' the electro-magnetic devices, a pair ot' reciprocable slides actuated in response to the action ot' the electro-magnetic devices, one of said slides carrying a pair of contacts adapted to engage said posts alternately to complete the circuit from said supply source through the electro-magnetic devices, and means for holding said contact carrying slide to complete the circuit through one electromagnetic device until the piston has completed its stroke and then permit it to move to complete the circuit through the other.

2. In a pump, in combination, a pump cylinder having an inlet and an outlet port, a cylinder head entirely enclosing each end of the cylinder, a piston reciprocating within the cylinder, an electro-magnetic device for moving the piston in each direction, an electrical supply source, a pair of spaced contact posts each connected with an electro-mag netic device, a reciprocating slide carrying a pair of contacts adapted to engage said posts ",altcrnately, a second slide reeiprocated in response to the action of said electro-magnetic devices and resiliently connected with the first slide, a stop for preventing movement ot the first slide with the second, and

a cam carried by the second slide adapted to release said stop to permit movement of the first slide when the piston nears the end of its stroke.

3. In a pump, in combination, a cylinder,

` a piston therein, electromagnetic means for reciprocating said piston in said cylinder, a switch for controlling the iow of current to said electromagnetic means, an actuator for said switch actuated by said electromagnetic means, a spring connecting said actuator and switch, means controlled by said actuator for restraining said switch, and means for retarding the movements of said actuator.

4. In a pump, in combination, a cylinder, a piston therein, a pair of solenoids for reciprocating said piston in said cylinder, said solenoids having pole pieces, a switch for controlling the flow of current to said solenoids, a slide guided on the exterior of said cylinder for reciprocation between said pole pieces and subjected to the attraction thereof, a spring connecting said slide and switch, detents for restraining said switch, said. detents being controlled by said slide, and a dash pot mechanism for retarding the movements of said slide under the attraction of said pole pieces.

5. In an electro-magnetic reciprocating mechanism, in combination, a magnetic plunger, two solenoids for reciprocating said plunger, and a switch mechanically separate trom said plunger and actuated by magnetic attraction induced by the energization of said solenoids for directing the flow of electric current to said solenoids alternately.

6. In an electro-magnetic reciprocating mechanism, in combination, a magnetic plunger, two solenoids tor reciprocating said plunger, said solenoids having fixed pole pieces, and a switch mechanically separate from said plunger and actuated by the attrae` tion of said pole pieces when said solenoids are energized ttor directing the flow of current to said solenoids alternately.

7. In an electro-magnetic reciprocating mechanism, in combination,4 a magnetic plunger, two solenoids for reciprocating said plunger, said solenoids having fixed pole pieces, a switch mechanically separate from said plunger and actuated by the attraction of said pole pieces when said solenoids are energized for directing the How of current to said solenoids alternately, and mechanism for retarding the movements of said switch.

8. In an electromagnetic reciprocating mechanism, in combination, a magnetic plunger, electromagnetic means for reciproeating said plunger, a switch for controlling the flow ot current to said electromagnetic means, and means actuaed by the magnetic teld surrounding said p anger for operating said switch.

9. In an electromagnetic reciprocating mechanism, in combination, a magnetic 

